Forces and stresses Flashcards
1
Q
What three forces can act on timbers?
A
- Compression
- Tension
- Shear
2
Q
Define compression
A
A force that is pushing down on an object
3
Q
Define tension
A
A force that is pulling an object apart
4
Q
Define shear
A
A force that is acting on opposite directions (e.g. pushing one up and the other side down)
5
Q
An example of a compression force.
A
Standing on an object
6
Q
An example of a tension force.
A
Tugging on the end of a rope
7
Q
An example of a shear force.
A
Cutting action of a scissor
8
Q
Define static force
A
A constant force being applied to an object
9
Q
Define dynamic force
A
A varying force being applied to an object
10
Q
How do static and dynamic forces affect timber?
A
- The static force of heavy branches and dynamic force of the wind blowing against a tree will all contribute to internal stresses affecting a tree trunk when it is converted into planks.
- When it is cut and sawn into planks, the stress is released from the wood and it bend and crack.
11
Q
What is a pre-stressed construction beam?
A
A pre-stressed beam is bent during construction to prevent it from bending as much during use due to tension forces.
